Roman's Son is the unborn child of late Roman Bellic. After the player determines to play the Deal ending mission, Mallorie Bardas-Bellic is widowed after her husband, Roman Bellic, who was accidentally shot during Niko Bellic's assassination outside the Church. After the mission, Mallorie contacts Niko and talks about her unborn child and the struggle that is destined when Roman's child is born without its father.
However, since the child never appears in the game and is never announced to be born, myths were determined to circulate regarding the existence of the child. Some myth hunters believe that the child is never born and Mallorie continues her struggle in the city, whereas some hunters claim that it may be seen in the succeeding GTA games, but these reports will remain a myth until Rockstar actually introduces Roman's descendant.
However, if the player chooses to follow the mission Revenge, Roman Bellic doesn't die but still calls Niko and tells him that he is soon going to be a father, but is uncertain about the gender of the child and further tells Niko that if it's a girl, she will be named Kate, Niko's late love interest.